English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present the results of formaldehyde and methanol deuteration measurementstowards the Class I low-mass protostar SVS13-A, in the framework of the IRAM30-m ASAI (Astrochemical Surveys At IRAM) project. We detected emission linesof formaldehyde, methanol, and their deuterated forms (HDCO, D2CO, CHD2OH,CH3OD) with Eup up to 276 K. The formaldehyde analysis indicates Tkin = 15 - 30K, n (H2) >= 10^6 cm^-3, and a size of about 1200 AU suggesting an origin inthe protostellar envelope. For methanol we find two components: (i) a hightemperature (Tkin = 80 K) and very dense (> 10^8 cm^-3}) gas from a hot corino(radius about 35 AU), and (ii) a colder Tkin <= 70 K) and more extended (radiusabout 350 AU) region.  The deuterium fractionation is 9 10^-2 for HDCO, 4 10^-3 for D2CO, and 2 - 710^-3 for CH2DOH, up to two orders of magnitude lower than the values measuredin Class 0 sources. We derive also formaldehyde deuteration in the outflow: 410^-3, in agreement with what found in the L1157-B1 protostellar shock.Finally, we estimate [CH2DOH]/[CH3OD] about 2. The decrease of deuteration inthe Class I source SVS13-A with respect to Class 0 sources can be explained bygas-phase processes. Alternatively, a lower deuteration could be the effect ofa gradual collapse of less deuterated external shells of the protostellarevelope. The present measurements fill in the gap between prestellar cores andprotoplanetary disks in the context of organics deuteration measurements.

Decrease of the organic deuteration during the evolution of Sun-like protostars: the case of SVS13-A